DENVER—The marijuana industry breathed a sigh of relief Friday after federal banking regulators issued long-awaited permission for them to access basic banking services. But Colorado’s pot pioneers said more needs to be done to bring the industry full legitimacy.

The U.S. Justice and Treasury departments issued guidance Friday intended to increase the availability of financial services for legal marijuana businesses that are licensed and regulated, while preserving the government’s enforcement power.

It was welcome news for marijuana businesses that have lost bank accounts and struggled to pay employees and taxes in cash.

“It’s made it very difficult to pay our bills, to pay our employees, to pay our taxes, to do anything,” said Caitlin McGuire, owner of Breckenridge Cannabis Club, a recreational marijuana shop.

At Seattle’s Conscious Care Cooperative, a medical marijuana dispensary with three branches and 11,000 members, business consultant Trek Hollnagel said the guidance “definitely looks exciting.”

He said the dispensary was always up front with banks about its line of business, and some, including Bank of America Corp., would let it open accounts—only to freeze or close them later on.

“From one day to the next, they changed their policies,” Hollnagel said. “If all your funds are frozen for two weeks, it makes it difficult to run a business. You write a rent check on a Monday, get a call from the bank Tuesday saying the account’s frozen, then a call from your landlord on Wednesday saying the check bounced.”

Still, business owners and industry advocates say the memo is just a beginning. They are hoping Congress will act to give them more certainty and expand access to things like insurance, loans and the federal courts.

“Banking is the first step. It’s a big first step. But it’s a first step,” said Dan Anglin, a lobbyist for EdiPure Brands, a Denver-based maker of edible marijuana with licensing agreements in four states.

“If we enter in an agreement with another entity and they violate that agreement, what is our recourse? A federal court isn’t going to recognize any breach of contract,” Anglin said. “Congress needs to act before our legitimate business concerns are addressed.”

Rep. Ed Perlmutter, who has sponsored a long-stalled pot-banking bill, said he’s optimistic Congress will act on banking, but it may be a couple years off.

“We gotta keep at this thing,” said Perlmutter, D-Colo.

He argued, however, that the banking guidance is an important development for federal authorities who see the problems of a cash-only business but still consider the business itself illegal.

“They’re trying to thread the hole in a tiny needle,” Perlmutter said.

The banking guidance could also help make pot shops safer, industry groups say. Though Colorado data on crimes at marijuana businesses don’t indicate that they attract robberies at rates different from other shops, dispensaries are sometimes compared to jewelry stores that can’t insure their diamonds. Some dispensary owners hire extra security to escort employees leaving the business. Others hire armored cars to transport cash.

“It is imperative that Congress not view today’s guidance as the ultimate solution to this public safety crisis. Congress must act quickly to solve the problem before we witness a tragedy,” said Michael Elliott, head of Colorado’s Medical Marijuana Industry Group.

Colorado regulators in recent years considered trying to regulate the industry using Bitcoin or state-chartered banks but ultimately could not arrive at a solution to the banking problems.

“There was no way to get around the federal part of this,” said Jack Finlaw, lawyer to Colorado Gov. John Hickenlooper, speaking at a forum earlier this week.